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10 Jul 2008, 19:32

The fossil remains of the first flying vertebrates, the pterosaurs, have intrigued paleontologists for more than two centuries. How such large creatures, which weighed in some cases as much as a piloted hang-glider and had wingspans from 8 to 12 meters, solved the problems of powered flight, and exactly what these creatures were—reptiles or birds—are among the questions scientists have puzzled over.Perhaps the least controversial assertion about the pterosaurs is that they were reptiles. Their skulls, pelvises, and hind feet are reptilian. The anatomy of their wings suggests that they did not evolve into the class of birds. In pterosaurs a greatly elongated fourth finger of each forelimb supported a wing-like membrane. The other fingers were short and reptilian, with sharp claws. In birds the second finger is the principal strut of the wing, which consists primarily of feathers. If the pterosaurs walked on all fours, the three short fingers may have been employed for grasping. When a pterosaur walked or remained stationary, the fourth finger, and with it the wing, could only turn upward in an extended inverted V-shape along each side of the animal’s body.The pterosaurs resembled both birds and bats in their overall structure and proportions. This is not surprising because the design of any flying vertebrate is subject to aerodynamic constraints. Both the pterosaurs and the birds have hollow bones, a feature that represents a savings in weight. In the birds, however, these bones are reinforced more massively by internal struts.Although scales typically cover reptiles, the pterosaurs probably had hairy coats. T. H. Huxley reasoned that flying vertebrates must have been warm-blooded because flying implies a high rate of metabolism, which in turn implies a high internal temperature. Huxley speculated that a coat of hair would insulate against loss of body heat and might streamline the body to reduce drag in flight. The recent discovery of a pterosaur specimen covered in long, dense, and relatively thick hairlike fossil material was the first clear evidence that his reasoning was correct.Efforts to explain how the pterosaurs became airborne have led to suggestions that they launched themselves by jumping from cliffs, by dropping from trees, or even by rising into light winds from the crests of waves. Each hypothesis has its difficulties. The first wrongly assumes that the pterosaurs’ hind feet resembled a bat’s and could serve as hooks by which the animal could hang in preparation for flight. The second hypothesis seems unlikely because large pterosaurs could not have landed in trees without damaging their wings. The third calls for high waves to channel updrafts. The wind that made such waves however, might have been too strong for the pterosaurs to control their flight once airborne.

1. It can be inferred from the passage that which of the following is characteristic of the pterosaurs?(A) They were unable to fold their wings when not in use.(B) They hung upside down from branches as bats do before flight.(C) They flew in order to capture prey.(D) They were an early stage in the evolution of the birds.(E) They lived primarily in a forest-like habitat.2.It can be inferred from the passage that some scientists believe that pterosaurs(A) lived near large bodies of water(B) had sharp teeth for tearing food(C) were attacked and eaten by larger reptiles(D) had longer tails than many birds(E) consumed twice their weight daily to maintain their body temperature

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10 Jul 2008, 19:46

First one was pretty tough, IMO A, because of "with it the wing, could only turn upward in an extended inverted V-shape along each side of the animal’s body".

Second one was relatively easier. IMO A again. Because of by rising into light winds from the crests of waves and the third calls for high waves to channel updrafts. The wind that made such waves however.

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10 Jul 2008, 20:24

abhijit_sen wrote:

First one was pretty tough, IMO A, because of "with it the wing, could only turn upward in an extended inverted V-shape along each side of the animal’s body".

Second one was relatively easier. IMO A again. Because of by rising into light winds from the crests of waves and the third calls for high waves to channel updrafts. The wind that made such waves however.

Please post the OAs.

Agree .The 1st one is kimd of tricky. But you got it right.

I think you have a copy paste issue with the explanation for the 2nd question

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10 Jul 2008, 20:29

goalsnr wrote:

Agree .The 1st one is kimd of tricky. But you got it right.

I think you have a copy paste issue with the explanation for the 2nd question

I think I have copied correctly but I did not edit it and put verbatim. But what basically I wanted to point is that P lived near area where waves, that too high enough so that P can launch it from them, were present. That means they lived near water bodies. I guess only large water bodies can have such large waves (remember we cannot factor technological things because although it may be possible now to create high waves in small water bodies but when P lived at that time such technology was perhaps non-existent).

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10 Jul 2008, 20:39

abhijit_sen wrote:

goalsnr wrote:

Agree .The 1st one is kimd of tricky. But you got it right.

I think you have a copy paste issue with the explanation for the 2nd question

I think I have copied correctly but I did not edit it and put verbatim. But what basically I wanted to point is that P lived near area where waves, that too high enough so that P can launch it from them, were present. That means they lived near water bodies. I guess only large water bodies can have such large waves (remember we cannot factor technological things because although it may be possible now to create high waves in small water bodies but when P lived at that time such technology was perhaps non-existent).

Is my answer correct or not? You did not confirm or reject it.

Yep,your answer is correct. The answer comes from the following para:Efforts to explain how the pterosaurs became airborne have led to suggestions that they launched themselves by jumping from cliffs, by dropping from trees, or even by rising into light winds from the crests of waves. Each hypothesis has its difficulties. The first wrongly assumes that the pterosaurs’ hind feet resembled a bat’s and could serve as hooks by which the animal could hang in preparation for flight. The second hypothesis seems unlikely because large pterosaurs could not have landed in trees without damaging their wings. The third calls for high waves to channel updrafts. The wind that made such waves however, might have been too strong for the pterosaurs to control their flight once airborne.

But the tricky part of this para is it doesn't explicitly mention water. It mentions waves - waves produced by winds.